1. Field of the Invention
This invention relates to a magnetic memory device, wherein information is magnetically written into or read out from a magnetic recording medium such as a magnetic disk, magnetic drum, a magnetic tape and the like through a magnetic head and the like.
2. Description of the Prior Art
In a magnetic memory device, information is magnetically written into and read out from said magnetic recording medium through the magnetic head (hereinafter referred to as the head) during which a magnetic head slider (hereinafter referred to as the slider) is maintained to contact with a magnetic recording medium (hereinafter referred to as the medium) or to be separated from the medium by a thin air gap. As this type of the magnetic memory device, a magnetic tape memory device, a magnetic card memory device, a flexible disk memory device and a hard disk memory device are commercially available.
In the flexible disk and the hard disk device of these magnetic memory devices, the head will be separated from the medium by a thin air gap when the medium is rotating due to an air pressure generated by the rotation of the medium. On the other hand, a spring is attached to the head in order to push the head toward the medium. Consequently, the head is maintained at certain position balancing a floating force by the air pressure with a force of the spring pushing the head against the medium. In all these magnetic memory devices wherein information is written into or read out from the medium through the head which is separated from the medium, it is necessary to maintain the slider close to the medium as much as possible in order to maximize the storage density. For this purpose, in case of the hard disk memory device for example, the width of air gap between the slider and the medium is maintained at 0.2 .mu.m in minimum.
In case the air gap is so much thin as mentioned above, flotation of the head will be disturbed by dust floating in the housing and become unstable thus causing problems that the head having unstable flotation and the medium contact each other which results in abrasion of the head and the medium. Also, head-crush will occur due to such contact of the head with the medium.